A generally similar anti-locking wheel control system is disclosed in the German laid-open application No. 22 58 317. The object of this known system is to recognize the special situations for the control system in which, despite the effective operation of the regulator, in the "wheels locked" state, the stopping distance is lengthened. Such special situations arise when driving on deep snow, slush, sand, gravel, etc., or with road conditions where a locked wheel penetrates a layer of limited frictional value and slides further onto a layer having a higher frictional value, while a regulated wheel rolls over the layer of limited frictional value.
In the known system, it is proposed to interrupt the control of one or more wheels at intervals when a danger of locking arises and thus to cause the wheel or wheels to lock. In accordance with the first proposed embodiment, the control is made ineffective at least on some of the wheels when the vehicle deceleration is between approximately 0.2 g and 0.5 g. In accordance with a second possible embodiment, it is determined whether the vehicle deceleration is greater with the control system operating or with locked wheels and on the basis of this comparison, the control system is switched off as necessary.
In accordance with a third proposed embodiment, the acceleration behavior of the wheel which is made to lock is monitored while the brakes are released. If the wheel acceleration is between 0.5 g and 2 g, then the control system is switched off.